Compute device housing with layers of electromagnetic interference shields, and devices and systems for the same

ABSTRACT

In some embodiments an apparatus includes a housing that defines an interior. The apparatus includes a first circuit board that has multiple integrated circuits (ICs). The first circuit board is disposed within the interior of the housing. The apparatus includes a second circuit board that has multiple ICs. The second circuit board is also disposed within the interior of the housing. The apparatus further includes a first electromagnetic interference (EMI) shield disposed about an IC from the multiple ICs of the first circuit board and not disposed about remaining ICs from the multiple ICs of the first circuit board. The apparatus further includes a second EMI shield disposed about the first circuit board and not the second circuit board. The apparatus further includes a third EMI shield disposed about the first circuit board and the second circuit board.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 16/895,880, filed Jun. 8, 2020, entitled “Compute Device HousingWith Layers Of Electromagnetic Interference Shields, And Devices AndSystems For The Same”, now U.S. Pat. No. 10,775,856, which claimspriority to and the benefit of U.S. Patent Application No. 62/942,372,filed Dec. 2, 2019 and entitled “Radio Frequency Filter,” each of whichis incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of electromagneticinterference shields, and in particular to apparatus, devices, andsystems related to a compute device housing, in which the compute devicehousing and electronic circuits inside the compute device housing areshielded using layers of electromagnetic interference shields.

BACKGROUND

Electronic circuitry including integrated circuits or power systems incomputers and embedded systems can generate electromagnetic waves thatcan induce undesired electromagnetic effects to other electroniccircuitry of the computers and embedded systems, and even can induceundesired electromagnetic effects outside of the computers and embeddedsystems. Thus, a need exists for an electromagnetic interferenceshielding that improves reliability and security of the computers orembedded computers.

SUMMARY

In some embodiments an apparatus includes a housing that defines aninterior. The apparatus includes a first circuit board that has multipleintegrated circuits (ICs). The first circuit board is disposed withinthe interior of the housing. The apparatus includes a second circuitboard that has multiple ICs. The second circuit board is also disposedwithin the interior of the housing. The apparatus further includes afirst electromagnetic interference (EMI) shield disposed about an ICfrom the multiple ICs of the first circuit board and not disposed aboutremaining ICs from the multiple ICs of the first circuit board. Theapparatus further includes a second EMI shield disposed about the firstcircuit board and not the second circuit board. The apparatus furtherincludes a third EMI shield disposed about the first circuit board andthe second circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that illustrates an integrated circuitshielding system, according to an embodiment.

FIG. 2 is a schematic side view of an integrated circuit shieldingsystem, according to an embodiment.

FIG. 3 is a block diagram that illustrates an integrated circuitshielding system, according to an embodiment.

FIG. 4 is a schematic description of an integrated circuit shieldingsystem, according to an embodiment.

FIG. 5 is a flowchart of a method for shielding a set of electromagneticinterferences, according to an embodiment.

DETAILED DESCRIPTION

Non-limiting examples of various aspects and variations of theembodiments are described herein and illustrated in the accompanyingdrawings.

One or more embodiments described herein generally relate to apparatusand systems that use a set of electromagnetic interference (EMI) shieldsto shield a set of integrated circuits (ICs) within an integratedcircuit shielding system. Generally speaking, operating a firstelectronic circuit of a compute device, ranging from small embeddedelectronic devices to large electronic systems, can generate unintendedelectromagnetic waves such as, for example, radio frequency waves,microwaves, and/or the like. Such unintended electromagnetic wavesgenerated by the first electronic circuit can induce undesiredelectromagnetic effects on a second electronic circuit of the computedevice and/or information crosstalk between the first electroniccircuit, the second electronic circuit, and/or to a third electroniccircuit outside the compute device. Such undesired electromagneticeffects and/or information crosstalk can pose degraded performance ofthe electronic circuit and information security, and can be reduced orprevented using the integrated circuit shielding system describedherein.

Described herein are examples of integrated circuit shielding systems(also referred to herein as “electronic shielding systems”) that aresuitable for highly reliable and secure computing systems. One or moreintegrated circuit shielding systems described herein achieve highperforming integrated circuit shielding, circuit board shielding, and/orelectronic device shielding that collectively protect the integratedcircuits, circuit boards, and/or electronic devices disposed in the oneor more integrated circuit shielding systems from a wide range ofpotential electromagnetic interference events. The potentialelectromagnetic interference events can include, for example, events atdifferent frequencies such as radio frequencies, microwave frequencies,and/or the like.

One or more integrated circuit shielding systems described herein areused to separate, via layers of interference filters, electroniccomponents (including integrated circuits and circuit boards) disposedwithin a chassis of the one or more integrated circuit shieldingsystems. Separating the electronic components by layers of interferencefilters reduces or eliminates undesired crosstalk between the electroniccomponents and potential inadvertent propagation of information betweenthe electronic components and/or the outside of the one or moreintegrated circuit shielding systems.

Electromagnetic interference (EMI) shielding performance of anelectronic shielding system described herein depends at least in part onindividual EMI shielding of each electronic component (e.g., anintegrated circuit (IC), a circuit board, and/or the like) disposedwithin the electronic shielding system. Having a shield located as closeas possible to a source of an unintended EMI radiation can reduce higherharmonic frequencies (also referred to herein as “harmonics”) of theunintended EMI radiation and protect individual electronic components.This is in contrast to having a catch-all electromagnetic filter with abroadband electromagnetic response that essentially cannot prevent anEMI radiation originated within the electronic system from negativelyimpacting an electronic component disposed also within the electronicshielding system. Moreover, relying solely on individual EMI shieldingof each electronic component cannot, in some instances, account for acollective generation of EMI radiations by multiple electroniccomponents or, in some instances, harmonics that are not fully blockedby individual EMI shields. Therefore, a multi-layer approach with alayer of an EMI shield(s) to shield EMI radiations by integratedcircuits, a layer of an EMI shield(s) to shield EMI radiations bycircuit boards, and a layer of an EMI shield(s) to shield all possibleremaining EMI radiations can be most effective as described herein.

FIG. 1 is a block diagram that illustrates an integrated circuitshielding system 100, according to an embodiment. The integrated circuitshielding system 100 includes a housing 110 that defines an interior ofthe housing 110. The housing 110 of the integrated circuit shieldingsystem 100 is a housing that helps to protect, mechanically support,and/or house various electronic components that make up the integratedcircuit shielding system 100.

A set of circuit boards 120, 130, and a set of electromagneticinterference (EMI) shields 151, 152, 153 (e.g., a part of a Faradaycage, a gasket, and/or the like) are disposed within the interior of thehousing 110. Additional electronic components such as for example, acooling fan, a thermal management device, a power supply, and/or thelike (not shown) can also be disposed within the interior of the housing110. In some implementations, a host board (e.g., a motherboard; notshown) that hosts various electronic components (e.g., the set ofcircuit boards 120, 130) and the EMI shields 151, 152, 153 of theintegrated circuit shielding system 100 can also be disposed within thehousing 110.

The set of circuit boards 120, 130 are boards that can mechanicallysupport and electrically interconnect electrical components (e.g., acapacitor(s), a resistor(s), an inductor(s), and/or the like) and/orelectronic components (transistors, light emitting diodes, logic gatecircuit, and/or the like). Each circuit board 120, 130 can furtherinclude conductive tracks (copper tracks, aluminum tracks, silvertracks, and/or the like), conductive sheets (copper sheets, aluminumsheets, and/or the like), insulating sheets (e.g., porcelain sheets,mica sheets, plastic sheets, and/or the like), and/or the like. Eachcircuit board from the set of circuit boards 120, 130 can be connected(without intervening components) or operatively coupled (with or withoutintervening components) to the remaining circuit boards from the set ofcircuit boards 120, 130. Each circuit board 120, 130 can provide atleast one specialized function such as, for example, computing, graphicprocessing, storage, networking, and/or the like. The set of circuitboards 120, 130 include a set of integrated circuits (ICs)121,122,131,132 that collectively perform the at least one specializedfunction. In some instances, each circuit board 120, 130 can performmultiple functions such as, for example, computing and storage, graphicprocessing and networking, storage and graphic processing, and/or thelike. Although only two circuit boards 120, 130 and four sets of ICs121,122,131,132 are shown in FIG. 1, it should be understood that thisis only for convenience and a greater number of circuit boards and setsof ICs are possible.

Each IC 121, 122, 131, 132 typically integrates a large number (e.g.,thousands, millions, and/or the like) of electronic components (e.g.,metal-oxide-semiconductor (MOS) transistors, charged-coupled opticalsensor, floating-gate memory cell, and/or the like) on a flat piece ofsemiconductor (e.g., silicon, germanium, gallium arsenide, and/or thelike), insulator (silicon oxide, silicon nitride, aluminum nitride,and/or the like), and/or conductor (silver, copper, indium tin oxide,and/or the like). The set of ICs 121, 122, 131, 132 can be configured toperform, for example, control procedures, arithmetic procedures, logicalprocedures, signal generation procedures, signal communicationprocedures, electronic charge storage procedures, and/or the like.

In some instances, an IC from the set of ICs 121, 122, 131, 132 caninclude a processor. The processor can include, for example, a generalpurpose processor, a graphical processing unit, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), anaccelerated processing unit (APU), a programmable logic controller(PLC), a microcontroller, and/or the like.

In some instances, an IC from the set of ICs 121, 122, 131, 132 caninclude a memory. The memory can include an electronic circuitry, amagnetic disk, and/or an optically encoded disk. The memory can beconfigured to be operatively coupled to the processor. The memory caninclude, for example, a memory buffer, a random access memory (RAM), aread-only memory (ROM), a hard drive, a flash drive, a secure digital(SD) memory card, a compact disk (CD), an external hard drive, anerasable programmable read-only memory (EPROM), an embedded multi-timeprogrammable (MTP) memory, an embedded multi-media card (eMMC), auniversal flash storage (UFS) device, and/or the like.

In some instances, an IC from the set of ICs 121, 122, 131, 132 caninclude a communication module. The communication module can enable theIC to communicate with (e.g., send data to and/or receive data from) theremaining ICs and/or external compute device via a wired connectionand/or a wireless communication. In some implementations, thecommunication module can include a set of transmitter antennas and/or aset of receiver antennas to enable the wireless communication (e.g., aWiFi™ wireless communication, a 5^(th) generation (5G) wirelesscommunication, a satellite communication, and/or the like). In someimplementations, the communication interface can establish and/ormaintain a communication session between the housing 110 and an externalcompute device (e.g., via a computer network or the internet, notshown).

In some implementations, the set of ICs 121, 122, 131, 132 are connected(without intervening components) or operatively coupled (with or withoutintervening components) to the remaining ICs from the set of ICs 121,122, 131, 132. For example, a processor IC can be operatively coupled toa memory IC via an address bus, a data bus, a control bus, and/or thelike (not shown). In some implementations, ICs (e.g., ICs 121, 122)included on a circuit board (e.g., circuit board 120) are operativelycoupled together but are not operatively coupled to the remaining ICs(e.g., ICs 131, 132) included in the remaining circuit boards (e.g.,circuit boards 130).

The set of electromagnetic interference (EMI) shields 151, 152, 153 aredisposed within the interior of the housing 110 of the integratedcircuit shielding system 100. The set of EMI shields 151, 152, 153 caninclude, for example, a part of a Faraday cage, an EMI gasket, and/orthe like. The set of EMI shields 151, 152, 153 can be made of continuoussheets of conductive materials (copper, aluminum, ferrite, MuMETAL™,Mylar blanket, and/or the like), patterned materials (metallic mesh,dielectric metamaterials, conductive foams, and/or the like), and/or anymaterial systems that are resistant to electromagnetic fieldpenetration. The set of EMI shields 151, 52, 153 are configured toshield, for example, a set of frequency harmonics (also referred toherein as ‘harmonics’) of an electromagnetic wave (e.g., a radiofrequency (RF) wave) generated within the interior of the housing 110.The set of EMI shields are disposed about a subset of ICs (e.g., IC 121and/or ICs 121, 131) from the set of ICs 121, 122, 131, 132, a subset ofcircuit boards (e.g., circuit board 120 and/or circuit board 130) fromthe set of set of circuit boards 120, 130.

In some embodiments, the integrated circuit shielding system 100 caninclude a set of compute devices (not shown) and/or to a set ofperipheral devices (not shown) communicatively and/or operativelycoupled to the housing 110 of the integrated circuit shielding system100. The set of compute devices can be outside the interior of thehousing 110 and can receive a set of signals from the set of circuitboards 120, 130. The set of compute devices can perform an action (e.g.,a communication, a remedial action, a computing action, a storageaction, and/or the like) in response to receiving the set of signalsfrom the set of circuit boards 120, 130. The set of compute devices caninclude, for example, a CPU, a memory, a GPU, a WiFi™ module, and/or thelike. The set of peripheral devices can be communicatively and/oroperatively coupled to the housing 110 of the integrated circuitshielding system 100. The set of peripheral devices can be set ofancillary devices used to input information to the set of circuit boards120, 130 of the housing 110 or output information from the set ofcircuit boards 120, 130 of the housing 110. The set of peripheraldevices can include, for example, a keyboard(s), a mouse(s), amonitor(s), a webcam(s), a microphone(s), a touch screen(s), aprinter(s), a scanner(s), a virtual reality (VR) head-mounted display, aspeaker(s), a headphone(s), a gamepad(s), a joystick(s), a biometricreader(s), and/or the like (not shown).

As shown in FIG. 1, the integrated circuit shielding system 100 includesa first electromagnetic interference (EMI) shield 151 (e.g., a part of aFaraday cage, a gasket, and/or the like) disposed about an IC 121disposed on the first circuit board 120 and not disposed about theremaining IC 122 on the first circuit board 120. The first EMI shield151 is disposed about the IC 121 in the sense that the first EMI shield151 at least partially surrounds the IC 121 in a three dimensional spacearound the IC 121 (e.g., partially surround on at least two sides of theIC 121 with a non-planar shape). The first EMI shield 151 can work inconjunction with another shielding component(s) to collectively andcompletely surround the IC 121. Although not shown in FIG. 1, anotherEMI shield can be disposed about IC 122 and not IC 121 (similar to firstEMI shield 151), and also can work in conjunction with another shieldingcomponent(s) to collectively and completely surround IC 122. The othershield component(s) with which the first EMI shield 151 and the EMIshield disposed about IC 122 works can be a common shield component(s)or separate shield component(s). Each of the first EMI shield 151 andthe EMI shield disposed about IC 122 can be physically connected and/oroperatively coupled to the other shielding component(s), for example, bysolder, spring tension, and/or a constant force applied by compressionfrom another component of system 100.

The integrated circuit shielding system 100 includes a second EMI shield152 (e.g., a part of a Faraday cage, a gasket, and/or the like) disposedabout the first circuit board 120 and not the second circuit board 130.Moreover, the second EMI shield 152 is disposed about the first EMIshield 151. The second EMI shield 152 is disposed about circuit board120 in the sense that the first EMI shield 152 at least partiallysurrounds the circuit board 120 in a three dimensional space around thecircuit board 120 (e.g., partially surround on at least two sides of thecircuit board 120 with a non-planar shape). The second EMI shield 152can work in conjunction with another shielding component(s) tocollectively and completely surround the first circuit board 120.Although not shown in FIG. 1, another EMI shield can be disposed aboutcircuit board 130 and not circuit board 120 (similar to second EMIshield 152), and also can work in conjunction with another shieldingcomponent(s) to collectively and completely surround circuit board 130.The other shield component(s) with which the second EMI shield 152 andthe EMI shield disposed about circuit board 130 works can be a commonshield component(s) or separate shield component(s). Each of the secondEMI shield 152 and the EMI shield disposed about circuit board 130 canbe physically connected and/or operatively coupled to the othershielding component(s), for example, by solder, spring tension, and/or aconstant force applied by compression from another component of system100.

The integrated circuit shielding system 100 further includes a third EMIshield 153 (e.g., a part of a Faraday cage, a gasket, and/or the like)disposed about the first circuit board 120 and the second circuit board130. The third EMI shield 153 is disposed about the first circuit board120 and the second circuit board 130 in the sense that the third EMIshield 153 at least partially surrounds the first circuit board 120 andthe second circuit board 130 in a three dimensional space around thefirst circuit board 120 and the second circuit board 130 (e.g.,partially surround on at least two sides of the first and second circuitboards 120, 130 with a non-planar shape). Moreover, the third EMI shield153 is disposed about the second EMI shield 152 and the first EMI shield151. The third EMI shield 153 can work in conjunction with anothershielding component(s) to collectively and completely surround the firstcircuit board 120 (and can be physically and/or operatively coupled tothe other shielding component(s) as described above in connection withthe first EMI shield 151 and the second EMI shield 152). The first EMIshield, the second EMI shield, and the third EMI shield are collectivelyconfigured to shield a harmonic EMI sent by the IC 121, a harmonic EMIgenerated by the first circuit board 120, and a harmonic EMIcollectively generated by the first circuit board 120 and the secondcircuit board 130, respectively. Although not explicitly shown forsimplicity, it should be understood that a separate EMI shield can bedisposed about each of ICs 122, 131, 132, and yet another separate EMIshield can be disposed about circuit board 130 so that each IC undergoesthree layers of EMI protection: one at the chip level, one at thecircuit board level, and one at the overall housing level.

In some implementations, the first EMI shield 151 surrounds the IC 121on all sides but one and is mounted on the first circuit board 120. Insuch implementations, the first EMI shield 151 surrounds the IC 121 fromthe lateral sides of the IC 121 and on the top side of the IC 121, butnot at the bottom side of the IC 121 where it is mounted on the firstcircuit board 120. The bottom side of the IC 121 mounted on the firstcircuit board 120 can be made of a printed circuit board (PCB) materialthat serves as an EMI shield and collectively with the first EMI shield151 define a Faraday cage. The Faraday cage fully surrounds the IC 121in a three dimensional space around the IC 121. In some implementations,the first EMI shield 151 includes a first portion that surrounds the IC121 on all sides but one and a second portion that corresponds to atleast a portion of the first circuit board 120 so that there is nointervening structure between the first EMI shield 151 and the IC 121.In one example, the EMI shield 151 can be directly and conformallydeposited on the IC 121 such that there is no air gap between the EMIshield 151 and the IC 121. In another example, the EMI shield 151 can bedirectly and conformally deposited on a dielectric encapsulation layercovering the IC 121. In yet another example, the EMI shield 151 can befabricated separately and placed on and/or about the IC 121 using amicro-positioner such that the EMI shield 151 surrounds the IC 121 withan air gap between the EMI shield 151 and the IC 121.

In some implementations, the second EMI shield 152 is included within(or is a part of) a Faraday cage that completely surrounds the firstcircuit board 120 in a three dimensional space around the first circuitboard 120. In some instances, the first circuit board 120 and/or thesecond circuit board 130 can be formed from or mounted, from the bottomsides, on top of a PCB board made of a PCB material that serves as anEMI shield. The second EMI shield 152 collectively with the PCB board atthe bottom side of the first circuit board 120 can define the Faradaycage.

In some implementations, the third EMI shield 153 is included within (oris a part of) a Faraday cage that completely surrounds the first circuitboard 120 and the second circuit board 130. The third EMI shield 153 canfurther include or be coupled to an EMI gasket. The third EMI shield 153collectively with the EMI gasket can collectively define the Faradaycage that surrounds the first circuit board 120 and the second circuitboard 130 in a three dimensional space around the first circuit board120 and the second circuit board 130. The third EMI shield 153 can be achassis for the entire system 100. For example, the third EMI shield 153as a chassis can be made from a single part or from multiple partscollectively grounded, so that a harmonic EMI is shielded.

In some configurations, the first EMI shield 151 is configured oroptimized to primarily shield a third harmonic EMI sent by the IC 121during operation of the IC 121. The second EMI shield 152 is configuredor optimized to primarily shield a fifth harmonic EMI sent by the ICs121, 122 and indirectly by the first circuit board 120 during operation(e.g., via a trace(s) of the first circuit board 120 during operation ofthe ICs 121, 122). The third EMI shield 153 is configured or optimizedto primarily shield a seventh harmonic EMI sent by the ICs 121, 122,131, 132, and indirectly the first circuit board 120 and the secondcircuit board 130 during operation (e.g., via a trace(s) of the firstcircuit 120 during operation of the ICs 121, 122 or a trace(s) of thesecond circuit board 130 during operation of the ICs 131, 132).

In some implementations, a selective shielding of a specific harmonicEMI (e.g., a third harmonic, a fifth harmonic, a seventh harmonic,and/or the like) can be achieved by patterning (or forming) the set ofEMI shields 151, 152, 153 with a set of apertures (e.g., circular holes,rectangular holes, elliptical holes, and/or the like). In one example,the radius of a circular aperture of an EMI shield can be based on acutoff frequency f_(c) of the EMI shield. In another example, thelongest dimension of a rectangular aperture of an EMI shield can bebased on a cutoff frequency f_(c) of the EMI shield. In some instances,to achieve an excellent shielding performance (e.g., over 90% shielding,over 99% shielding, and/or the like) in an EMI shield for the specificharmonic EMI, a longest dimension of apertures in the EMI shield can bekept at or smaller than a fraction (e.g., 1/20, 1/50, and/or the like)of the EMI wavelength of the specific harmonic EMI.

In some implementations, a selective shielding of a specific harmonicEMI can be achieved by configuring or optimizing the set of EMI shields151, 152, 153 with a thickness at or larger than an effective skin depthof a set of constituent materials of the set of EMI shields 151, 152,153. In one example, an EMI shield can be made of a continuous coppersheet having a skin depth of about 65 μm for an electromagneticradiation with 1 MHz frequency.

In some implementations, a selective shielding of a specific harmonicEMI can be achieved by configuring or optimizing the set of EMI shields151, 152, 153 (e.g., using analytical or numerical models) with acombination of material thicknesses and patterned apertures. The set ofEMI shields 151, 152, 153 can be configured/optimized to have aband-pass response. The band-pass response can reduce/block the specificharmonic of EMI while permitting propagation of another electromagneticwave.

In some instances, harmonics of a set of interferences at frequenciesless than and including a frequency associated with the seventh harmonicof the interference due to operation of the IC 121 are dominant (i.e.,have larger amplitudes than the amplitudes at higher frequencies). Insuch instances, the first EMI shield, the second EMI shield, and thethird EMI shield are collectively configured to shield interference (1)of electronic components within the interior of the housing and (2) atfrequencies less than and including a frequency associated with theseventh harmonic of the interference during operation of the electroniccomponents within the interior of the housing.

Selective shielding of specific harmonic EMIs about a set of EMI sources(e.g., the set of ICs 121, 122, 131, 132 and/or the set of circuitboards 120, 130) can be performed near the set of EMI sources. Suchselective shielding of a harmonic EMI near an EMI source can reduce orprevent the otherwise generation of higher harmonics of the harmonic EMIupon interaction of the harmonic EMI with surroundings of the EMIsource. Moreover, selective shielding of a specific harmonic EMI about afirst EMI source disposed within the housing 110 can reduce or prevent apotential negative or unintentional impact of the first EMI source onanother EMI source(s) also disposed within the housing 110. Although insome implementations the EMI shield 153 can be configured or optimizedto have a broadband response to include shielding effect for EMIs atmultiple frequencies including a third EMI harmonic, a fifth EMIharmonic or a seventh EMI harmonic, it is generally desirable toselectively shield each EMI harmonic near the EMI source.

In one example, an IC 121 of the integrated circuit shielding system 100includes a processing unit (not shown) that generates a set of clocksignals (e.g., electrical signals) for synchronized operation of a setof arithmetic operations of the processing unit. Besides the set ofclock signals, the IC also radiates a (parasitic) electromagneticinterference, for example, due to alternating current flowing in acircuitry of the IC. The electromagnetic interference generated at theIC can radiate in every direction and in high frequency (HF) band, veryhigh frequency (VHF) band, ultra-frequency (UF) band, and/or a frequencyin the same order of the clock speed. The spectral features of theelectromagnetic interference includes a set of odd harmonics and/or aset of even harmonics, where the set of odd harmonics are morepronounced than the set of even harmonics. The set of EMI shields of thecan be configured to shield the set of odd harmonics such as, forexample, a third harmonic of electromagnetic interference, a fifthharmonic of electromagnetic interference, a seventh harmonic ofelectromagnetic interference, and/or the like.

In some embodiments, a fourth EMI shield can be disposed about thesecond circuit board 130 and not be disposed about the first circuitboard 120. The second EMI shield 152 and the fourth EMI shield disposedaround the first circuit board 120 and the second circuit board 130,respectively, can define continuous ground planes for the first circuitboard 120 and the second circuit board 130. The second EMI shield 152and the fourth EMI shield can define the continuous ground planes byconnecting, via conductive material (e.g., a composite material withmetallic stands), to a grounded material. In one example, the groundedmaterial can be electrically connected to a power supply disposed withinthe interior of the housing 110.

FIG. 2 is a schematic side view of an integrated circuit shieldingsystem 200, according to an embodiment. As shown in FIG. 2, anintegrated circuit shielding system 200 includes a housing 210 thatdefines an interior. A first circuit board 220 and a second circuitboard 230 are disposed within the interior of the housing 200. The firstcircuit board 220 and the second circuit board 230 include a set ofintegrated circuits (ICs) 221, 222, 231, 232 that are also disposedwithin the interior of the housing 210. The first circuit board 220includes ICs 221, 222 and the second circuit board 130 includes ICs 231,232. Each circuit board 220, 230 and each IC 221, 222, 231, 232 areindividually and/or collectively shielded by an electromagneticinterference (EMI) shield from a set of EMI shields 251A, 251B, 251C,251D, 252A, 252B, 253 (e.g., a part of a Faraday cage, a gasket, and/orthe like) disposed within the interior of the housing 210 and about theIC 221, 222, 231 and the circuit board 220, 230. Each EMI shield 251A,251B, 251C, 251D, 252A, 252B, 253 can be configured to shield a harmonicEMI generated by an IC from the set of ICs 221, 222, 231, 232 and/or aharmonic EMI generated by the first circuit board 220 and/or the secondcircuit board 230.

Each IC from the set of ICs 221, 222, 231, 232 is electromagneticallyshielded by EMI shields 251A, 251B, 251C, 251D, respectively. Each EMIshield 251A, 251B, 251C, 251D surrounds an IC 221, 222, 231, 232,respectively on all sides but one. For example, the EMI shield 251Asurrounds the IC 221 from the lateral sides and on the top side of theIC 221, but not from the bottom side of the IC 121 where it is mountedon the first circuit board 220. In some implementations, each EMI shield251A, 251B, 251C, 251D surrounds an IC 221, 222, 231, 232, respectively,on all sides but one such that there is no intervening structure betweenthe EMI shield 251A, 251B, 251C, 251D and the IC 221, 222, 231, 232,respectively. In one example, an EMI shield 251A can be directlydisposed on the IC 221 such that there is no air gap between the EMIshield 251A and the IC 221. In another example, the EMI shield 251A canbe directly and conformally deposited on a dielectric encapsulationlayer covering the IC 221.

Each circuit board 220, 230 disposed in the interior of the housing 210of the integrated circuit shielding system 200 is electromagneticallyshielded by an EMI shield from a second subset of EMI shields 252A,252B. The EMI shield 252A, 252B surrounds the circuit boards 220, 230,respectively, on all sides but one. For example, the EMI shield 252Asurrounds the circuit board 220 from the lateral sides and on the topside of the circuit board 220, but not from the bottom side of thecircuit board 220 where it can be mounted on an interior surface of thehousing 210, a mechanical support disposed in the interior of thehousing 210, a motherboard disposed in the interior of the housing 210,and/or the like. The first circuit board 220 and the second circuitboard 230 (and the ICs mounted thereon) are electromagnetically shieldedby an EMI shield 253, encompassing the first circuit board 220 and thesecond circuit board 230 from all sides. In some alternativeembodiments, the first circuit board and the second circuit board can beelectromagnetically shielded by the EMI shield surrounding the firstcircuit board and the second circuit board on all sides but one.

In some implementations, the top surface of the first circuit board 220and/or the second circuit board 230 can be made of printed circuit board(PCB) materials that serve as EMI shields. Each EMI shield 251A, 251B,251C, 251D includes a first portion that surrounds each IC 221, 222,231, 232, respectively, on all sides but one and a second portion thatcorresponds to at least a portion (the top surface) of the first circuitboard 220 and/or the second circuit board 230 so that no interveningstructure is disposed between the first EMI shield and the IC. The firstportion and the second portion of each EMI shield can collectivelydefine a Faraday cage that fully surrounds each IC 221, 222, 231, 232 ina three dimensional space around each IC 221, 222, 231, 232.

FIG. 3 is a block diagram that illustrates an integrated circuit shieldsystem 300, according to an embodiment. The integrated circuit shieldsystem 300 includes a housing 310 and a set of circuit boards 320. Theintegrated circuit shield system 300 further includes a first set of EMIshields 341 disposed about a uniquely associated IC from a set of ICs330 of the set of circuit boards 320 and not disposed about eachremaining IC from the plurality of ICs 330. The integrated circuitshield system 300 further includes a second set of EMI shields 342, eachEMI shield from the second set of EMI shields disposed about a uniquelyassociated circuit board from the set of circuit boards 320 and notdisposed about each remaining circuit board from the set of circuitboards 320. The integrated circuit shield system 300 further includes athird EMI shield 343 disposed within the interior of the housing 310 andabout the set of circuit boards 320 and the set of ICs 330. The firstset of EMI shields 341, the second set of EMI shields 342, and the thirdEMI shield, each is configured to shield harmonics of a primaryfrequency of a radio frequency (RF) wave generated by an RF source (e.g.the set of ICs 330, the set of circuit boards 320, and/or the like).

FIG. 4 is a schematic description of an integrated circuit shieldingsystem 400, according to an embodiment. Note the right portion of FIG. 4shows a side view of the integrated circuit shield system 400 where theright half is shown in with cut-away to show RF source 450, shieldportions 460 and 470, and circuit board 480. The integrated circuitshielding system 400 includes a radio frequency (RF) source 450 (e.g.,an integrated circuit and/or a circuit board) disposed in the interiorof the integrated circuit shielding system 400 that generates a set ofradio frequency signals. The integrated circuit shielding system 400includes a set of integrated circuits (not shown) mounted on a set ofcircuit boards (not shown), other than the RF source 450, that are alsodisposed in the interior of the integrated circuit shielding system 400.The integrated circuit shielding system 400 includes two electromagneticinterference (EMI) shields (also referred to herein as the ‘layers ofradio frequency filters’) to shield the set of integrated circuits andthe set of circuit boards from the RF source 450. The first EMI shieldis defined collectively by shield portions 460 and 470, and is disposedabout the RF source 450 on all sides but one, and can be mounted on acircuit board 480 from the set of circuit boards such that there is nointervening structure between the first EMI shield and the RF source450. Therefore, the first EMI shield formed by shield portions 460 and470 can be configured to filter primary frequencies originating from theRF source. (A second EMI shield is not shown in this embodiment but canbe included in accordance with the other embodiments described here.)The third EMI shield is defined collectively by continuous ground plane410, composite material 420, grounded material 430 and EMI shield 440,and disposed about the set of circuit boards included in the integratedcircuit shielding system 400. The third EMI shield can define acontinuous ground plane 410 by connecting, via a composite material 420with or without metallic stands, to a grounded material 430. Moreover,the grounded material 430 can fill in a hole otherwise formed betweenthe continuous ground plane 410 and the composite material 420. Suchhole (if not filled with the grounded material 430) could otherwise belarge enough to allow EMIs to propagate through. As such, the third EMIshield can be configured to eliminate residual resonant frequencies ofthe RF source. The third EMI shield can have a cutoff frequency f_(c)that is based on a set of radii of a set of holes on the body of the EMIshield 440. On the other hand, the third EMI shield can serve as acatch-all electromagnetic filter with a broadband filtering response. Insome instances, to achieve an excellent shielding performance against aset of harmonic EMIs, a longest dimension of the set of holes of thethird EMI shield can be kept at or smaller than a fraction (e.g., 1/20,1/50, and/or the like) of a wavelength of a smallest wavelength of theset of harmonic EMIs. Hence, the third EMI shield can be used inparticular to eliminate harmonics of a primary frequency originated fromthe RF source.

FIG. 5 is a flowchart of a method 500 for shielding a set ofelectromagnetic interferences (EMIs), according to an embodiment. Themethod 500 can be implemented/performed by an integrated circuitshielding system (similar to the integrated circuit shielding system 100shown and described with respect to FIG. 1). At 501, the integratedcircuit shielding system is configured to shield a third harmonic ofinterference sent by an integrated circuit (IC) (e.g., the IC 121 asshown and described with respect to FIG. 1) during operation of the IC.At 502, the integrated circuit shielding system is configured to shielda fifth harmonic of interference sent by a first circuit board (e.g.,the circuit board 120 as shown and described with respect to FIG. 1)during operation of the first circuit board. At 503, the integratedcircuit shielding system is configured to shield a seventh harmonic ofinterference sent by the first circuit board and a second circuit boardduring operation of the first circuit board and the second circuitboard. Such shielding of the third harmonic of interference, a fifthharmonic of interference, and/or a seventh harmonic of interference canbe achieved by a set of EMI shields of the integrated circuit shieldingsystem having a set of holes with a size selected based on the thirdharmonic of interference, a fifth harmonic of interference, and/or aseventh harmonic of interference. Alternatively or in addition, theselective shielding can be achieved by configuring or optimizing the setof EMI shields with a thickness at or larger than an effective skindepth of the set of EMI shields, which is based on the third harmonic ofinterference, a fifth harmonic of interference, and/or a seventhharmonic of interference.

It should be understood that the disclosed embodiments are notrepresentative of all claimed innovations. As such, certain aspects ofthe disclosure have not been discussed herein. That alternateembodiments may not have been presented for a specific portion of theinnovations or that further undescribed alternate embodiments may beavailable for a portion is not to be considered a disclaimer of thosealternate embodiments. Thus, it is to be understood that otherembodiments can be utilized, and functional, logical, operational,organizational, structural and/or topological modifications may be madewithout departing from the scope of the disclosure. As such, allexamples and/or embodiments are deemed to be non-limiting throughoutthis disclosure.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

Examples of computer code include, but are not limited to, micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter. For example, embodiments can be implemented using Python,Java, JavaScript, C++, and/or other programming languages anddevelopment tools. Additional examples of computer code include, but arenot limited to, control signals, encrypted code, and compressed code.

The drawings primarily are for illustrative purposes and are notintended to limit the scope of the subject matter described herein. Thedrawings are not necessarily to scale; in some instances, variousaspects of the subject matter disclosed herein can be shown exaggeratedor enlarged in the drawings to facilitate an understanding of differentfeatures. In the drawings, like reference characters generally refer tolike features (e.g., functionally similar and/or structurally similarelements).

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range is encompassed within the disclosure. That the upper andlower limits of these smaller ranges can independently be included inthe smaller ranges is also encompassed within the disclosure, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the disclosure.

The phrase “and/or,” as used herein in the specification and in theembodiments, should be understood to mean “either or both” of theelements so conjoined, i.e., elements that are conjunctively present insome cases and disjunctively present in other cases. Multiple elementslisted with “and/or” should be construed in the same fashion, i.e., “oneor more” of the elements so conjoined. Other elements can optionally bepresent other than the elements specifically identified by the “and/or”clause, whether related or unrelated to those elements specificallyidentified. Thus, as a non-limiting example, a reference to “A and/orB”, when used in conjunction with open-ended language such as“comprising” can refer, in one embodiment, to A only (optionallyincluding elements other than B); in another embodiment, to B only(optionally including elements other than A); in yet another embodiment,to both A and B (optionally including other elements); etc.

As used herein in the specification and in the embodiments, “or” shouldbe understood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the embodiments, “consisting of,” will refer to the inclusion ofexactly one element of a number or list of elements. In general, theterm “or” as used herein shall only be interpreted as indicatingexclusive alternatives (i.e., “one or the other but not both”) whenpreceded by terms of exclusivity, such as “either,” “one of,” “only oneof,” or “exactly one of” “Consisting essentially of,” when used in theembodiments, shall have its ordinary meaning as used in the field ofpatent law.

As used herein in the specification and in the embodiments, the phrase“at least one,” in reference to a list of one or more elements, shouldbe understood to mean at least one element selected from any one or moreof the elements in the list of elements, but not necessarily includingat least one of each and every element specifically listed within thelist of elements and not excluding any combinations of elements in thelist of elements. This definition also allows that elements canoptionally be present other than the elements specifically identifiedwithin the list of elements to which the phrase “at least one” refers,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, “at least one of A and B” (or,equivalently, “at least one of A or B,” or, equivalently “at least oneof A and/or B”) can refer, in one embodiment, to at least one,optionally including more than one, A, with no B present (and optionallyincluding elements other than B); in another embodiment, to at leastone, optionally including more than one, B, with no A present (andoptionally including elements other than A); in yet another embodiment,to at least one, optionally including more than one, A, and at leastone, optionally including more than one, B (and optionally includingother elements); etc.

In the embodiments, as well as in the specification above, alltransitional phrases such as “comprising,” “including,” “carrying,”“having,” “containing,” “involving,” “holding,” “composed of,” and thelike are to be understood to be open-ended, i.e., to mean including butnot limited to. Only the transitional phrases “consisting of” and“consisting essentially of” shall be closed or semi-closed transitionalphrases, respectively, as set forth in the United States Patent OfficeManual of Patent Examining Procedures, Section 2111.03.

What is claimed is:
 1. An apparatus, comprising: a housing defining aninterior; a first circuit board having a plurality of integratedcircuits (ICs) and disposed within the interior of the housing; a secondcircuit board having a plurality of ICs and disposed within the interiorof the housing; a first electromagnetic interference (EMI) shielddisposed about an IC from the plurality of ICs of the first circuitboard and not disposed about remaining ICs from the plurality of ICs ofthe first circuit board; a second EMI shield disposed about the firstcircuit board and not the second circuit board; and a third EMI shielddisposed about the first circuit board and the second circuit board, thethird EMI shield configured to shield an electromagnetic wave that has aradio frequency and that is generated within the interior of thehousing.
 2. The apparatus of claim 1, wherein: the third EMI shield isconfigured to shield the electromagnetic wave that has the radiofrequency and that is generated by at least one of (1) the IC, (2) thefirst circuit board, or (3) the second circuit board.
 3. The apparatusof claim 1, wherein: the first EMI shield is configured to shield anelectromagnetic wave that has a radio frequency and that is generated bythe IC, and the second EMI shield is configured to shield anelectromagnetic wave that has a radio frequency and that is generated bythe first circuit board.
 4. The apparatus of claim 1, wherein: the ICgenerates a first EM wave having a radio frequency during operation ofthe IC, the first EMI shield is configured to shield a second EM wavethat has a radio frequency and that is a harmonic of the radio frequencyof the first EM wave, the second EMI shield is configured to shield athird EM wave that has a radio frequency and that is a harmonic of theradio frequency of the first EM wave, and the third EMI shield isconfigured to shield a fourth EM wave that is a harmonic of the radiofrequency of the first EM wave.
 5. The apparatus of claim 1, wherein:the first EMI shield has a first band-pass response and is configured toshield a third harmonic of interference sent by the IC during operationof the IC and not a fifth harmonic of interference and not a seventhharmonic of interference sent by the IC during operation of the IC, thesecond EMI shield has a second band-pass response and is configured toshield a fifth harmonic of interference sent by the first circuit boardduring operation of the first circuit board and not a seventh harmonicof interference sent by the first circuit board during operation of thefirst circuit board, and the third EMI shield has a third band-passresponse and is configured to shield a seventh harmonic of interferencesent by the first circuit board and the second circuit board duringoperation of the first circuit board and the second circuit board. 6.The apparatus of claim 1, wherein: the first EMI shield has a firstband-pass response and is configured to shield a third harmonic ofinterference sent by the IC during operation of the IC and not a fifthharmonic of interference and not a seventh harmonic of interference sentby the IC during operation of the IC, the second EMI shield isconfigured to shield a fifth harmonic of interference and not a seventhharmonic of interference sent by the IC and each remaining IC from theplurality of ICs from the first circuit board during operation of theplurality of ICs from the first circuit board, and the third EMI shieldhas a third band-pass response and is configured to shield a seventhharmonic of interference sent by the IC, each remaining IC from theplurality of ICs from the first circuit board, and each IC from theplurality of ICs from the second circuit board, during operation of theplurality of ICs from the first circuit board and the plurality of ICsfrom the second circuit board.
 7. The apparatus of claim 1, wherein: thefirst EMI shield has a first band-pass response, the second EMI shieldhas a second band-pass response and the third EMI shield has a thirdband-pass response, and the first EMI shield, the second EMI shield andthe third EMI shield are collectively configured to shield interference(1) of electronic components within the interior of the housing and (2)at frequencies less than and including a frequency associated with theseventh harmonic of the interference during operation of the electroniccomponents within the interior of the housing.
 8. The apparatus of claim1, wherein: the second EMI shield is disposed about the first EMIshield, and the third EMI shield is disposed about the second EMIshield.
 9. The apparatus of claim 1, wherein: the second EMI shield isincluded within a Faraday cage that completely surrounds the firstcircuit board, and the third EMI shield is included within a Faradaycage that includes an EMI gasket and that completely surrounds the firstcircuit board and the second circuit board.
 10. The apparatus of claim1, further comprising: a first plurality of EMI shields that includesthe first EMI shield, each EMI shield from the first plurality of EMIshields disposed about a uniquely associated IC from the plurality ofICs of the first circuit board and not disposed about each remaining ICfrom the plurality of ICs of the first circuit board; and a secondplurality of EMI shields, each EMI shield from the second plurality ofEMI shields disposed about a uniquely associated IC from the pluralityof ICs of the second circuit board and not disposed about each remainingIC from the plurality of ICs of the second circuit board.
 11. Theapparatus of claim 10, further comprising: a third plurality of EMIshields that includes the second EMI shield, each EMI shield from thethird plurality of EMI shields disposed about a uniquely associatedcircuit board from a plurality of circuit boards and not disposed abouteach remaining circuit board from the plurality of circuit boards, theplurality of circuit boards disposed within the interior of the housingand including the first circuit board and the second circuit board. 12.An apparatus, comprising: a housing defining an interior; a plurality ofcircuit boards disposed within the interior of the housing; a firstelectromagnetic interference (EMI) shield disposed about an IC of acircuit board from the plurality of circuit boards; a second EMI shielddisposed about the first EMI shield and the circuit board and not aremaining circuit board from the plurality of circuit boards; and athird EMI shield disposed about the second EMI shield and the pluralityof circuit boards, the third EMI shield configured to shield anelectromagnetic wave that has a radio frequency and that is generated byat least one of (1) the IC, (2) the circuit board, or (3) the remainingcircuit board from the plurality of circuit boards.
 13. The apparatus ofclaim 12, wherein: the IC is included within a plurality of ICs of thecircuit board, the first EMI shield is not disposed about each remainingIC from the plurality of ICs, the second EMI shield is not disposedabout each remaining circuit board from the plurality of circuit boards.14. The apparatus of claim 12, wherein: the first EMI shield has a firstband-pass response and is configured to shield a third harmonic ofinterference sent by the IC during its operation, the second EMI shieldhas a second band-pass response and is configured to shield a fifthharmonic of interference sent by the circuit board during operation ofthe circuit board, and the third EMI shield has a third band-passresponse and is configured to shield a seventh harmonic of interferencesent by the plurality of circuit boards during operation of theplurality of circuit boards.
 15. The apparatus of claim 12, wherein: thefirst EMI shield has a first band-pass response, the second EMI shieldhas a second band-pass response, and the third EMI shield has a thirdband-pass response, and the first EMI shield, the second EMI shield andthe third EMI shield are collectively configured to shield interference(1) of electronic components within the interior of the housing and (2)at frequencies less than a frequency associated with the seventhharmonic of the interference during operation of the electroniccomponents within the interior of the housing.
 16. The apparatus ofclaim 12, wherein the first EMI shield surrounds the IC on all sides butone and is mounted to the circuit board.
 17. The apparatus of claim 12,wherein the first EMI shield includes a first portion that surrounds theIC on all sides but one and a second portion that corresponds to atleast a portion of the circuit board so that no intervening structure isdisposed between the first EMI shield and the IC.
 18. The apparatus ofclaim 12, wherein: the second EMI shield is disposed about the first EMIshield, and the third EMI shield is disposed about the second EMIshield.
 19. An apparatus, comprising: a housing defining an interior; afirst circuit board having a plurality of integrated circuits (ICs) anddisposed within the interior of the housing; a second circuit boardhaving a plurality of ICs and disposed within the interior of thehousing; a first plurality of electromagnetic interference (EMI) shieldsthat includes the first EMI shield, each EMI shield from the firstplurality of EMI shields disposed about a uniquely associated IC fromthe plurality of ICs of the first circuit board and not disposed abouteach remaining IC from the plurality of ICs of the first circuit board,a second plurality of EMI shields, each EMI shield from the secondplurality of EMI shields disposed about a uniquely associated IC fromthe plurality of ICs of the second circuit board and not disposed abouteach remaining IC from the plurality of ICs of the second circuit board,and a third plurality of EMI shields, each EMI shield from the thirdplurality of EMI shields disposed about a uniquely associated circuitboard from a plurality of circuit boards and not disposed about eachremaining circuit board from the plurality of circuit boards, theplurality of circuit boards disposed within the interior of the housingand including the first circuit board and the second circuit board. 20.The apparatus of claim 19, further comprising: a third EMI shielddisposed about the first circuit board and the second circuit board.